For producing engines of recent automobiles, there is a known cylinder bore processing apparatus that carries out finish processing while providing the cylinder block with a deformation which corresponds to the deformation when a cylinder head is actually fastened to the cylinder block by means of a bolt. According to this processing apparatus, as disclosed in Japanese Patent Application Laid-open (JP-A) No. 2008-223503, a dummy head corresponding to the cylinder head is mounted on the cylinder block, a portion near the cylinder bore is pressed by a force corresponding to a pressing force caused by the bolt fastening, the cylinder bore is deformed, and the deformed cylinder bore is honed.
According to this processing apparatus, an engine can be produced in which deformation of the cylinder bore caused by a fastening force when the cylinder head is actually fastened by a bolt is taken into consideration. Accordingly, roundness of the cylinder bore when the engine is actually operated can be improved.
In engines of recent automobiles, especially in engines having aluminum cylinder blocks, in order to enhance heat radiation performance and a compression ratio, a metal (iron or the like) sprayed film is formed on the cylinder bore inner peripheral surface as a cylinder liner, and the resulting sprayed film is honed and finished.
The sprayed film is formed by plasma spraying metal to the cylinder bore inner peripheral surface from spraying means, and a protection mask apparatus is used so that the injected spraying particles do not scatter and adhere unnecessarily.
Such a protection mask apparatus is disclosed in JP-A No. 2002-339053, which includes a hollow cylindrical outer portion disposed on an upper surface of a cylinder block so as to surround a cylinder bore and an insertion member detachably provided on an inner peripheral surface of the outer portion (also called a separate type protection mask apparatus). There is also a protection mask apparatus in which a coating layer is formed on an inner peripheral surface of an outer portion (also called an integral type protection mask apparatus).